#include <atomic>
#include <chrono>
#include <condition_variable>
#include <iostream>
#include <thread>
using namespace std::chrono_literals;

std::condition_variable cv;
std::mutex cv_m;
std::atomic<int> i{0};

void waits(int idx) {
  std::unique_lock<std::mutex> lk(cv_m);
  auto now = std::chrono::system_clock::now();
  if (cv.wait_until(lk, now + idx * 100ms, []() { return i == 1; }))
    std::cerr << "Thread " << idx << " finished waiting. i == " << i << '\n';
  else
    std::cerr << "Thread " << idx << " timed out. i == " << i << '\n';
}

void signals() {
  std::this_thread::sleep_for(120ms);
  std::cerr << "Notifying...\n";
  cv.notify_all();
  std::this_thread::sleep_for(100ms);
  i = 1;
  std::cerr << "Notifying again...\n";
  cv.notify_all();
}

int main() {
  std::thread t1(waits, 1), t2(waits, 2), t3(waits, 3), t4(signals);
  t1.join();
  t2.join();
  t3.join();
  t4.join();
}
